This invention relates to vascular procedures and more particularly to a docking assembly for the extension of a guidewire with an extension wire comprising socket means and plug means for axial engagement into said socket means.
It is common practice to use a guidewire for the placement of a catheter in vascular procedures such as angioplasty. A guidewire typically is slightly longer than the catheter with which it is used, whereby a relatively short portion of the guidewire protrudes proximally from the catheter when the catheter is in place. If it becomes necessary to exchange the catheter, for instance to increase the balloon size in an angioplasty procedure, the guidewire must be removed and replaced by an exchange wire which is about twice the length of the catheter in order to allow withdrawal of the catheter and insertion of a new catheter over the exchange wire. However, this technology seriously complicates and slows down the vascular procedure, and there have been several attempts to attach an extension wire to the initial guidewire in order to eliminate the need of a separate exchange wire.
European Patent No. 0321796 A2 describes an extendable guidewire system comprising a main guidewire section and a guidewire extension section and a connection therebetween including a tubular member fixed to the end of one of the guidewire sections and a male member arranged on the end of the other guidewire section which has a maximum radial dimension which is greater than the inner diameter of the tubular member, whereby the male member may be inserted into the tubular member to releasably secure the two guidewire sections together. According to a first embodiment, the male member is shaped into an undulating or sinusoidal shape. According to a second embodiment, the male member is provided with a smaller diameter portion having radial protrusions.
Hence, deformation of the undulating shape of the male member or relative deformation of the male member with radial protrusions provide for a friction fit of the male member into the tubular member and the two guidewire sections may be connected or disconnected as desired. The need for radial deformation to generate the friction fit requires a distinct difference in diameter between the inner diameter of the tubular member and that of the male member. Therefore, the male member has to be extremely thin and it may be easily bent inadvertently, thereby ruining the guidewire section to which it belongs. Furthermore, as the insertion of the male member into the tubular member is made against friction forces, these forces may cause buckling, and even total kinking in the case of a male member with sinusoidal shape, also ruining the corresponding guidewire section.
U.S. Pat. No. 4,917,103 shows a guidewire system in which a steel tubular connector is attached to the proximal end of a guidewire and a reduced diameter steel tip is attached to the distal end of an extension wire. The contrary is also possible, with the tubular connector on the extension wire and the reduced diameter tip on the guidewire. For connecting the extension wire to the guidewire, the reduced diameter tip is inserted into the tubular connector and the assembly of both the tip and connector is crimped by means of appropriate pliers used as a crimping tool. Mechanical attachment of both parts is thus obtained by displacing a segment of both the tubular connector and tip inserted therein laterally of their common axis in what may be considered as a generally U-shaped configuration. The extent of lateral displacement is of course selected so that it will not interfere too much with the smooth advancement of a catheter over the point of assembly. To release or disconnect the assembly of guidewire and extension wire, it is necessary to cut the guidewire distally of the crimp or to break the connection at the location of the crimped tubular connector and tip assembly. The system is thus a permanent connection, and when released by cutting the guidewire or breaking the connector and tip assembly, both the guidewire and extension wire are ruined, so that the system is definitely not re-usable. In addition, the cutting-out of the guidewire or the breaking of the connector and tip assembly may prove difficult or even impossible without some special cutting tool. And this adds to the fact that the need to use a crimping tool for the mechanical attachment of the tubular connector and tip renders the system dependent from the proper use of the crimping tool.
U.S. Pat. No. 5,188,621 disclosed an extendable guidewire assembly in which the guidewire has a tapered proximal end, the extension wire has a tapered distal end, and a polymeric tubular sleeve is affixed concentrically about one of either the proximal end of the guidewire or the distal end of the extension wire. The sleeve is so made as to have its lumen expanding radially when the sleeve is under axial compression and to contract radially when the sleeve is under axial tension; furthermore, the lumen of the sleeve has a diameter which is smaller than the untapered diameter of the wire to which the sleeve is not fixedly attached. To connect the assembly, the tapered end of the wire to which the sleeve is not fixedly attached is inserted into the sleeve until a tight friction fit between the sleeve and the tapered end is achieved. Because of the so-called "Chinese finger tube" fit, the connection between the sleeve and tapered end inserted therein will be verified upon applying axial tension to both wires; disconnection will be achieved only by placing a gripping force on the end face of the sleeve in which is inserted the tapered end of the wire not fixedly attached to the sleeve, and pulling said tapered end from the lumen of the sleeve. This assembly is thus providing a self acting connection which needs however manipulations and skill to be disconnected.
U.S. Pat. No. 5,113,872 describes a guidewire extension system comprising an extension guidewire adapted to be releasably connected to a proximal end of an initial guidewire. The distal end of the extension guidewire is mounted in a tube in which is located an open pitch flat wire coiled spring one end of which is placed over the distal end of the extension guidewire and welded thereto; the other end of the coiled spring extends freely in the tube and a detent arranged at the end of the tube prevents the free end of the spring from being moved out of the tube. To achieve connection of the extension guidewire to the initial guidewire, the ground down proximal end of the initial guidewire is inserted into the tube and urged therein until it engages the coiled flat wire spring and bottoms against the distal end of the extension guidewire. As the proximal end of the initial guidewire is inserted into the coils of the flat wire coiled spring, the coils are forced to slightly uncoil so that they can receive the outer diameter of the proximal end of the initial guidewire. Then, any axial force pulling the proximal end of the initial guidewire away from the coiled spring causes the coils around said proximal end to move towards a smaller diameter and that tendency establishes a connection between the coils and proximal end. Any pull on the extension guidewire causes axial extension of the coiled spring, which results in a reduction of the diameter of the coils and greatly increases the locking forces of the coiled spring against the proximal end of the initial guidewire. To disconnect the assembly it is necessary to rotate the extension guidewire in order to loosen the grip of the coiled spring against the proximal end of the initial guidewire and at the same time to pull the initial guidewire out of engagement with the coils of the flat wire coiled spring. This assembly also provides a self acting connection which is however dependent on manipulations and skills to be disconnected.
U.S. Pat. No. 5,247,942 shows a guidewire arrangement with swivel capacity, comprising a main part, an extension part, and a connector. The connector joins the main part to the extension part such that the main part and extension part may be rotated relative to each other. In one embodiment devised as an attachable extension, the arrangement provides for a socket attached to one of the parts and a plug attached to the other part. The socket comprises a resilient bolting snap which protrudes inwardly of the socket. The plug is terminated by a cylindrical part forming a circular trap adapted to catch the resilient bolting snap of the socket. The assembly is obtained by inserting the plug into the socket whereby the cylindrical part of the plug lifts the resilient bolting snap which then falls down behind the cylindrical part to be caught by the cylindrical part to lock the assembly. As a result, this connection is not detachable. And for small diameters the socket and its resilient bolting snap is difficult to manufacture. It may be therefore difficult to achieve reliably reproducible snapping and locking forces on randomly combined guidewires and extensions.
It is an object of this invention to improve the possibilities of attaching an extension wire to a guidewire and to avoid the aforesaid drawbacks. Still a further object of the invention is to achieve attachment and release of a guidewire and extension wire by means of a docking assembly which is simple, inexpensive and easy to manufacture, which guarantees a smooth, efficient and repetitive operation for both connection and release of the guidewire and extension wire, and which does not require skills or troublesome manipulations, and which provides reliably reproducible locking and unlocking conditions on randomly combined guidewires and extensions.